Graves' disease is a common disease of the thyroid caused by autoimmunity and can produce serious complications including cardiac problems and eye disease. Environmental factors play some role, but development of disease is strongly conditioned by genetic factors including inheritance of specific HLA Class II genes, and a specific version of the CTLA-4 gene. We have previously investigated the role of Class II MHC genes in Graves' disease through their presentation of T cell epitopes derived from the TSH receptor on antigen presenting cells, to T cells, in the development of immunity. We have shown that certain TSH receptor epitopes, which frequently stimulate T cells from patients with Graves' disease, bind with moderate affinity to HLA-DRbetal*0301. We will study the interaction of TSH receptor epitopes, HLA proteins, and T cells to better understand the development of disease and methods for possible inhibition of the immune process. Binding of TSH receptor epitopes to all of the DR and DQ proteins commonly found in our Graves' patients will be detailed and related to the genotype of the patient and reactivity of T cells from patients with the same genotype. Using computer algorithms, affinity studies, and T cell responses, as well as information gained from sequencing eluted epitopes from DR protein, we will establish the important or immunodominant TSH receptor T cell epitopes. With this information in hand, we will attempt to derive mutated TSH receptor sequences which inhibit the response of patients' T cells to TSH receptor epitopes. We will also use TSH receptor epitopes bound in DR or DQ molecules, or in tetramers, to remove reactive T cells from patient blood samples in vitro to determine whether a method can be found to reduce immunoreactivity. In a model of Graves' disease in TSH-R-immunized mice, we will develop epitopes that may inhibit the disease process, including the development of ophthalmopathy. Such epitopes might similarly be used in patients in the future. Our studies will be done in collaboration with Dr. A. Godkin, who will analyze TSH-R epitopes in a computer algorithm, Dr. R .G. Phelps, who will analyze TSH-R epitopes which we elute from DR3 molecules, Dr. W. Kwok, who will provide DR3 tetramers, and with Dr. M. Ludgate on the model of Graves' disease.